1. Field of the Invention
The invention concerns a tightening frame for a tarpaulin, especially for mounting on a truck or truck trailer with a frame profile and an anchor profile that has, on its long edge facing the tarpaulin, a rounded-off foot, which can be inserted into one of optionally several rounded-off grooves of the frame profile or an intermediate profile connected to it and pivoted in it, in which case the anchor profile, by pivoting around its foot, enters the tightened state of the tarpaulin and a position parallel to the plane of the tarpaulin, and in which either the anchor profile or a weather-stripping profile connected to pivot with it has at least one receptacle for a weather strip, corresponding to the introductory part of claim 1.
2. Description of the Prior Art
This type of tightening frame is disclosed in WO 01/35382 A. FIGS. 15 to 30, in particular, of this document show a variant in which the tightening conditions for the tarpaulin can be easily varied by a number of parallel ledges, in which the frame is intrinsically secured in the rest state by the geometric dimensions, i.e., without additional fastenings, against undesired opening. However, the following must be said concerning this:
The upper weatherstrip profile is exposed by the tension of the tarpaulin to a counterclockwise torque, in FIG. 30, around the suspension point on the frame profile. This would lead to a reduction in tension of the tarpaulin, but the weatherstrip profile, due to its edge extending upward and toward the plane of the frame (not shown), cannot be rotated so that selected ledges remain fixed on the notch of the frame profile.
The situation is similar on the lower edge of the tarpaulin: tension of the tarpaulin exposes the weatherstrip profile to a clockwise torque around its pseudojoint (roughly in the center of the profile, formed by the end of the protruding part of the frame profile). Movement in the clockwise direction around this point, however, is hampered by the tarpaulin profile, on which the end of the weatherstrip profile away from the tarpaulin is suspended. This tightening profile is also exposed to a clockwise torque and, on the other hand, is supported on the frame (not shown) with its widely protruding end. However elegant this solution appears to be at first glance, it is problematic in practice: Because of the far protruding arm of the frame profile on whose ends the pivot axes of the weatherstrip profile are formed as pseudoaxes, large bending moments and bending stresses occur that must be tolerated over the entire service life of the profile even during rough operation without permanent deformation. To this, it must be added that the entire tensile force of the tarpaulin acts on the outermost ends of these arms, which makes an overload very easily possible during application of the tarpaulin by the tightening profile.
Finally, the intrinsic security of the tightening frame depends exclusively on contact of the outermost edges of the weatherstrip profile or tightening profile on the components that are not part of the frame, which, on the one hand, leads to high bending stresses and the tendency toward plastic deformations or rupture because of the absence of any other support of this profile and, on the other hand, requires corresponding design of the components to carry the frame.
The design of the profile is not appropriate for reliably maintaining intrinsic security in the case of vibrations, or in the case of penetration and freezing of water in the gaps between the frame or the frame's surroundings and the weatherstrip profile or tightening profile, inevitably causing opening of the tightening frame.
Another drawback is that discrete snap-in possibilities into the profile acting on the tarpaulin are only provided on the tightening side opposite the tightener or tightening device. Moreover, the profile separates where no tightening is present, so that handling of the tarpaulin or profile by a single person is almost impossible.
Another type of frame is disclosed in EP 0 495 688 A1 and in a variant that comes closest to the invention, according to FIGS. 4a and 4b of this document. However, these figures show a tightening device for a tarpaulin in which, even in the end position, a torque always remains in the opening direction of the tightening device because of tension in the tightened tarpaulin; it is therefore not intrinsically secure. Even during the use of fixed poster walls or the like, this tightening device must always be additionally secured, which occurs in the depicted case by an elastic snap connection. This tendency for opening of the tightening device also exists when the two tightening frames are not arranged, as disclosed, normal to the actual tarpaulin surface, but run in the plane of the tarpaulin, since even then the connection or deflection edges that are necessarily provided cause torque in the opening direction. In addition, the device known from EP 0 495 688 A1 offers no possibility for easy and simple adaptation of tightening or adjustments to different tarpaulin sizes, as can be the case, for example, during expansion of the fabric exposed to tension for a longer time. For example, during adjustment of tarpaulin tightening on the frame, the tightening profile must be threaded around a different weatherstrip groove.
In comparison with this, the invention seeks to devise a so-called intrinsically secure tightening device, which is understood to mean a device that is held in the closed position by the tension in the tarpaulin. The fact that in different applications, such as in the tarpaulins of trucks or the like, additional fastening can be provided as an additional means of security, changes nothing in the objective of this intrinsic security.
U.S. Pat. No. 5,893,227 A discloses a tightening frame similar to the one in the aforementioned documents, but in which the possibility of simple and rapid adaptation to alter tightening conditions can be achieved due to the presence of several groove-like recesses (these can also be called hook-like protrusions). The problem of intrinsic security, however, also fully exists here and is solved by an outer profile that is snapped over the entire frame so that tilting away of the actual tarpaulin holder in the opening direction is prevented. The tightening devices in this tightening frame also lie in a plane that runs normal to the plane of the tarpaulin and, unlike EP 0 495 688 A1, an arrangement within or parallel to the plane of the tarpaulin is not possible here, since securing with the outer profile no longer functions and the tightening frame can no longer be used.
In comparison with this prior art, the task of the invention is to devise a tightening frame that does not have these drawbacks.
A tightening frame in which the individual frame components are much more favorably loaded than in the aforementioned document, but which, as follows especially from FIGS. 9 and 10, is not intrinsically secure but requires additional fastening, is known from EP 1 271 456 A. In addition, this tightening frame, interestingly, is only adjustable so that the weatherstrips of the tarpaulin are threaded out over the entire length of the tightening frame and threaded back into another of the numerous weatherstrip receptacles of the frame. This need for the threading in and threading out of the weatherstrip is extremely time-consuming and irksome, also requiring considerable room because of the length of the frame and the rigidity of the weatherstrip, and cannot be performed everywhere without problems.
This was obviously also recognized by the inventor of the device according to the aforementioned document, which led to U.S. Pat. No. 6,209,245 B, in which the adjustability of tightening is guaranteed by a sawtooth profile and a counterprofile, but in which any type of tightening frame that can be mounted by folding or pivoting is dispensed with and in which intrinsic security also plays no role, since the tightening frame is fastened by screws, which is to be avoided, in principle, by the invention and would be permitted only as an additional expedient, if at all (prevention of theft, etc.).
WO 03/030133 A discloses a tightening frame that is intrinsically secure, but uses a winding bar instead of a weatherstrip to hold the tarpaulin edge, which is rejected by users in practice. The reason for this rejection is not only the irksome winding of the winding rod with the tarpaulin edge because it must be precise and in which the edge can be several meters long, but also the fact that creeping of the tarpaulin along the winding rod cannot be ruled out over longer periods due to tightening of the tarpaulin, especially during vibrations. Also, dimensional changes caused by heat make it so that additional fastening of the tarpaulin on the winding rod is always necessary in practice, with the advantages of a winding rod relative to the weatherstrip (folding of the tarpaulin is readily possible, and the edge of the tarpaulin requires no special handling) being lost because of this.
Since the intrinsic security of the device according to WO 03/030133 A depends on the shape of the frame profile, especially in the area of its hook, as well as the intermediate profile adapted to it and the winding rod in order to achieve intrinsic security, this tightening frame could not be reconfigured for the use of a weatherstrip profile. To this we must add that because of the V-shaped design of the hook of the frame profile, strong bending movements and bending forces are exerted on the hooks, which require a corresponding massive and therefore expensive design, similar to the aforementioned WO 01/35382A.
Even if all this is considered and improved, this tightening frame still lacks easy adjustability, as is already achieved by other already known tightening frames.
Another tightening frame is known from WO 00/79507 A1. In this case the frame profile has several rows of hook-like protrusions into which a counterhook of the tarpaulin profile can be hooked. This must occur during tightening of the tarpaulin and requires a tool. Opening of the connection also requires a tool, so that replacement of the tarpaulin or its tightening, if it has expanded with time, is a demanding process.
A tarpaulin tightener that is actually a type of belt tightener is known from DE 199 15 927 A1 and is connected to the tarpaulin edge by means of a connection element. A tightener lever then works cooperatively with a tarpaulin holder that is adjustable in length and therefore determines the tightening. This device is mounted in predetermined spacings along the edge of the tarpaulin and adjusted individually, which at first glance increases the flexibility, but in actual operation only increases the adjustment work. Because of individual mounting of each tightener, the cost of installation is high and, during installation, each individual tightener must be operated separately, which is time-consuming.
Generally, as stated in WO 00/79507 A1, so-called weatherstrip profiles are commonly used for the fastening of tarpaulins to frames. These profiles are connected around the tarpaulins to the tarpaulin edge and have a bulge or thickening parallel to the tarpaulin edge that can work with a counterprofile of the frame. In ordinary, essentially rectangular tarpaulins, two adjacent sides with bulges are pushed into the counterprofile of a fixed frame; the two other sides are pushed into a counterprofile of a so-called anchor. The fixed frame profiles are mounted on a truck structure, on the house wall, or wherever the tarpaulin is to be fastened, with a counterprofile for the two anchors being fastened at a spacing that essentially corresponds to the spacing of the bulges of the tarpaulin.
These counterprofiles have grooves at relatively narrow spacings, into which a ledge of the anchor profile can be pushed. Because of the narrow spacings, it is possible to tighten the tarpaulin accordingly in order to select the best possible matching groove for introduction of the ledge of the anchor. Introduction of the ledge into the groove occurs with a tool, since substantial forces are required to keep the tarpaulin tight. In most cases the anchors are then screwed at a certain spacing, but at least in the areas of the corners by screwing with the profile having the grooves in order to prevent opening of the clamp during vibrations, shaking and, for example, during freezing of water that has penetrated into the area of the groove or ledge.
In most cases it is necessary to provide the frame profile equipped with grooves on three sides, since insufficient space is generally available for insertion of the bulge of the weatherstrip into a fixed frame profile, so that anchors are provided on three sides of the tarpaulin. The expenditure to be incurred in the course of assembly and disassembly is significant and ultimately the tight and optically attractive assembly is formed, as is essential during use of the tarpaulin as an advertising surface, but because of the precise fastening of the weatherstrip on the tarpaulin edge, corrections to the position of a weatherstrip once installed are almost ruled out. To this we must add that the ledge of the anchor on three sides of the tarpaulin must be forced into the correct groove of the frame with a tool.
Consequently, there is a demand for a fastening system for a tarpaulin that does not have the mentioned drawbacks and permits the tarpaulin to be changed quickly without problems and without tools and, at least in one embodiment, permits the disassembled tarpaulin to be folded or rolled up to the extent that the tarpaulin is acceptable per se without additional restrictions being required.